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標題: | 氫原子頻譜儀於股骨頭內脂質成分分析:
對缺血性骨壞死之探討 Proton Magnetic Resonance Spectroscopy ─ Evaluation of lipid Composition and Assessment of Avascular Necrosis of the Femoral Head |
作者: | Chun-han Hou 侯君翰 |
指導教授: | 施庭芳(Ting-Fang Shih),楊榮森(Rong-sen Yang) |
關鍵字: | 磁振造影,氫原子頻譜儀,股骨頭,缺血性骨壞死,非外傷性,類固醇,脂肪增生,骨髓,脂類,水份, Magnetic Resonance Image (MRI),Proton Magnetic Resonance Spectroscopy (1H MRS),Femoral Head,Avascular Necrosis,Non-traumatic,Corticosteroid,Lipogenesis,Bone Marrow,Lipid,Water, |
出版年 : | 2006 |
學位: | 碩士 |
摘要: | 股骨頭缺血性骨壞死的可能成因有血管栓塞、靜脈壓增加,或血管炎等,但常常發生骨內壓上升,改變骨頭之血流灌注變化而形成。髓質骨在股骨頭內形成許多密閉的小室間隔,其內組織只要稍有變化,即可引起骨內壓力上升,導致小血管坍塌而血流減少造成缺血;而股骨頭含量最豐富的為其黃骨髓中的脂肪。類固醇使用為缺血性骨壞死的重要因素之一,它可造成脂肪細胞肥大及不正常沈澱,並刺激特殊基因﹝422(aP2)﹞表現,促使骨前身細胞分化為脂肪細胞。基於此,作者認為探討骨髓內脂肪成份的變化,應可對缺血性骨壞死作進一步了解及預測。
過去對骨壞死的評估均以氫原子的磁振影像為主,如T1或T2影像,及顯影劑注射後的增影為主;從未曾利用氫原子的頻譜儀。氫原子的頻譜儀常被用於評估大腦疾病如癲癇、急性腦梗塞等;而脂肪本身亦含豐富氫原子,所以其成份及結構的分析,氫原子頻譜儀為適當可行的方法,同樣的;水份子亦有豐富的氫原子,所以可以利用氫頻譜來測量骨頭中水及脂肪之成份比例。近幾年來,曾有人把頻譜儀中的PRESS、STEAM、QCSI等技術用來研究人體腰椎椎體內的脂肪及水份,以觀測血癌病人,再生性不良貧血及高瑟氏病人的骨髓內脂肪與水份異常,並比較治療前後的不同;它也被用於測量正常人在不同年紀、性別的差異。 第一階段,我們的實驗組為單側股骨頭壞死病人,將氫原子頻譜儀用在他們另外一側於臨床上無症狀、X光沒有變化、MRI完全正常的股骨頭上。對照以年齡相符、而無髖關節疾患之病人。我們發現,在這兩組當中,脂肪與水在頻譜儀的波形,有顯著的變化。也就是說,在這些病人「看似健康」的對側股骨頭裡,脂肪與水的比例已經改變了。 但由於不能在病人身上做切片檢查,因此我們不能斷定,這種脂肪與水比例上的變化,是否真的代表該側的股骨頭已經有早期壞死的現象。同時,因為這是一個斷面性的研究(cross sectional study),沒有經過長時間的追蹤,我們也不能斷定,氫原子頻譜儀所顯示的變化,可以早期診斷股骨頭壞死,也不能作為判斷預後的工具。 因此,同樣的一批實驗組病人,經過至少兩年的追蹤後,再次施以核磁共振和氫原子頻譜儀的檢查。這就是第二階段的研究。我們預期,應可以發現,有部分的病患,在原本健康的那一側,產生股骨頭壞死的現象。 另外,根據先前文獻顯示,股骨頭缺血性骨壞死和成年後形成的生長板疤痕(epiphyseal scar)有關。有些人的生長板疤痕是完整的(complete),將股骨頭和股骨頸的血液灌流分離,這些人,相較於不完整(incomplete)生長板的另外一群人,會有比較高的比率,發生股骨頭缺血性骨壞死。 因此,我們在兩年後,針對實驗組的病患,分別對股骨頭及股骨頸的部位做氫原子頻譜儀的取樣。根據生長板疤痕的完整與否,可以分為兩組。我們很好奇,生長板疤痕的完整與否,會不會影響股骨頭和股骨頸,在氫原子頻譜儀上的波形?(脂肪和水的比例是否改變?) 在第二階段的研究裡,我們追蹤實驗組的38位病患,並對他們正常那側的股骨頭進行核磁共振及頻譜儀的檢查。在頻譜儀的波形中,脂肪的訊號被細分成三個波峰,分別位於2.1ppm, 1.2ppm,及 1.0ppm。我們用三個變數去描述每一個波峰:integration, amplitude, 和line width。生長疤痕的完整與否也被紀錄,作為一個預後因子。 38個病人裡面,有四位(10.5%)病人在兩年的追蹤期內併發了新的股骨頭壞死,且都是男性。這四個病人和其餘的34位健康病人相比,位於2.1ppm和1.0ppm脂肪波峰的integration有顯著差異。而在2.1ppm處的波峰,amplitude也顯示有顯著差異。至於新併發股骨頭壞死和生長疤痕並沒有統計上的關連。 容易發生股骨頭壞死的病人,和一般病人相比,在2.1ppm處的脂肪波峰有顯著的變化。根據其他文獻顯示,這一部份的脂肪波峰可能代表酯類的官能基。也就是說,這類病人的脂質成分(化學的官能基)已經改變了。將來應持續以動物實驗或病理切片研究等方式來證實此點。 氫原子頻譜儀上脂肪的頻譜表現,或許可以在預測股骨頭壞死疾病的進展上,扮演一定的角色,甚至可以提早至兩年前就有發現。 The etiology of avascular necrosis of the femoral head might be thromboembolism of small vessels, increased venous pressure and vasculitis. Increased intraosseous pressure is an important factor of the occurrence of avascular necrosis of the femoral head. The changes of the intramedullary, extravascular component not only influence the intraosseous pressure, but also alter the blood perfusion of the femoral head. The cancellous bone make the bone marrow space septated into many small, closed chamber within the femoral head. Thus, only minimum alteration in the intramedullary component can increase the intraosseous pressure of femoral head and make the small vessel collapsed. Impaired blood perfusion and then ischemia developed subseguently. The major component within the femoral head is the fatty tissue of its yellow bone marrow. The medication of corticosteroid is an important predisposing factor of avascular necrosis, the steroid can cause fat cell hypertrophy and abnormal deposition. The steroid can also stimulate the osteoprogenitor cells to express a fat cell specific gene, 422(aP2), and to differenciate into adipocytes. Based on these above mentioned reasons, the investigator plan to figure out the change of fat component within the bone marrow of femoral head, and may have more understanding and prediction about avascular necrosis. According to the previous report, the evaluation of avascular necrosis was majorly based on the proton magnetic resonance image, such as T1 and T2 weighted images and enhancement pattern with contrast agent injection. The proton magnetic resonance spectroscopy (1H MRS) was never used. The 1H MRS was commonly used in evaluating the cerebral disorders, such as epilepsy and acute infarction. The fat itself has plenty of proton and 1H MRS will to be the appropriate method evaluate the fat tissue. The water also had plenty amount of proton. Thus, we consider the possibility to evaluate the ratio of intraosseous fat and water by using the proton MRS. In recent years, several investigators started to use the PRESS, STEAM or QCSI technignes to study the fat and water component of human vertebral body. They also found the lipd-water ratio demonstrated by 1H MRS was abnormal in patients with leukemia, aplastic anemia and Gaucher disease. The therapeutic result was also followed by 1H MRS. Not only the patients, but also the normal subjects were studied with 1H MRS according to different age and gender. In phase I of the study, we applied the proton MRS examination on the intact femoral heads of patients with unilateral osteonecrosis of hip. These hips are symptomless and normal on plain films and MRI films. Age-matched controls without hip problems were also measured. Our results revealed significant difference between these two groups in the lipid and water components of the femoral heads. However, due to lack and impossibility of biopsy, we can not be certain that the differences indicate early change of osteonecrosis. In addition, it is a cross-sectional study without long-term follow-up, we also can not be sure that the MRS can diagnose osteonecrosis earlier than MRI, nor as a prognostic predictor. Therefore, we perform MRI and MRS study again after at least two years. It is the phase II of the study. We expect that some patients should develop osteonecrosis on their previously intact hips. According to our literature review, femoral head avascular necrosis is related to epiphyseal scar after adulthood. Some people have complete epiphyseal scar which separates the blood supply from femoral neck to femoral head; others have incomplete epiphyseal scar. These patients with complete epiphyseal scar have higher osteonecrosis rate. Therefore we perform MRS study both on femoral head and femoral neck region. We divide our patients into “complete” and incomplete” groups. We are curious that whether these two groups have different MRS waveform, that is, different lipid and water component. In phase II, MRS was performed on the intact hips of 38 patients with unilateral femoral AVN. They were followed and MRS study was performed after at least two years. The lipid spectrum on the MRS was further divided into three peaks, at 2.1ppm, 1.2ppm and 1.0ppm . Three variables were used to describe each peak: integration, amplitude, and line width. The completeness of epiphyseal scar was also recorded as a prognostic factor. 10.5% (4/38) patients developed a new AVN lesion on the previous intact femoral heads in a two-year follow-up period. They are all male. In lipid peaks at 2.1 and 1.0ppm, the integration showed significant differences between these four patients and the rest 34 patients (p<0.05). In the lipid peak at 2.1ppm, the amplitude showed significant differences (p<0.05). The risk of AVN progression is not related to the completeness of epiphyseal scar. The lipid peak at 2.1ppm showed significant change in the patients who was prone of develop new AVN lesions. According to the literature, these part of the lipid may represent the ester group. In other words, the lipid composition had changed, by transforming its chemical compounds in certain ways, in the high risk patients. Further animal study and pathologic examination is required to correlate the spectroscopic findings. The lipid spectrum of MRS on the femoral head at risk of AVN could play a role in predicting its prognosis of possible progression into AVN, as early as two years. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/32628 |
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